Production Update:
Starter Fertilizer: Nitrogen is often recommended at planting time
as a starter fertilizer for alfalfa. Nitrogen fertilizer may stimulate
growth of alfalfa seedlings. However, nitrogen may also stimulate growth
of weeds and will delay nodulation until the nitrogen level in the soil
is decreased. The amount of nitrogen applied as a starter fertilizer should
be in the range of 25 to 50 pounds of N per acre and rates above 50 pounds
of N per acre and considered excessive.

Insect Management: The granulate cutworm, Agrotis subterranea
(Fabricius), is a devastating pest of bed planted alfalfa and is also
an occasional pest of flood irrigated alfalfa. The cutworm larvae (picture)
often go undetected until after cutting or hay removal. When fields are
watered back, there may be areas of little or no regrowth due to cutworms
feeding on new shoots from alfalfa crowns. Granulate cutworm is nocturnal
and will move from cracks in the soil or from under duff in the evening
and climb into the alfalfa canopy to feed. Some of the cutworms feed on
new shoots under the duff, holding back regrowth, depleting starch reserves
in the crowns and thereby weaken the plants. Weakened plants are more
susceptible to disease. Permethrin, cyfluthrin and Steward are insecticides
that control this pest. Cutworms feeding under the duff may escape insecticide
treatments.

Issued in furtherance of Cooperative Extension work, acts
of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture,
James A. Christenson, Director Cooperative Extension, College of Agriculture
and Life Sciences, The University of Arizona.

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